1. Field of the Invention
The invention is related to the field of communications, and in particular, to a wrap path for ring access control circuitry.
2. Statement of the Problem
Packet communications and communication rings are well known communication technologies. One example of packet communications is the use of the Internet Protocol (IP), and one example of a communication ring is a Synchronous Optical Network (SONET) ring. Resilient packet ring technology combines the efficiency of packet communications with the fault-tolerance of a communication ring. Resilient packet rings are described in I.E.E.E. standard 802.17.
If a link in a ring fails, then nodes adjacent to the failed link perform a wrap—a routing of traffic away from the failed link. The part of the node that performs the wrap is referred to as ring access control circuitry. Typically, a pair of rings are implemented together, and each node on the rings has mated ring access control circuits—one circuit to control each ring.
Unfortunately, there are a few problems with the current ring access control circuitry for resilient packet rings. These problems are illustrated in detail below with regard to FIGS. 1–3, but a brief summary is provided here. Current ring access control circuitry requires that a host system coupled to the node be configured to perform traffic steering away from the failed link in the event of a wrap. This may add undesirable complexity to the host. In addition, a wrap effectively disables one of the flow control agents in the ring access control circuitry of a wrapped node. As a result of losing the flow control agent, the available bandwidth at the node is significantly diminished.